I can't recommend Bakers Creek. They ship their seeds with not one scrap of planting or harvesting information. I had to guess as to when and how deep to plant some of the more "exotic" varieties. Next year I'll try one of the other heirloom seed catalogues.

I will add a few...
Johnny's Selected Seeds & Territorial Seeds, while they also sell hybrids, carry quite a few heirlooms, and both also have their own excellent open-pollinated varieties from their in-house breeding programs.

Bountiful Gardens has a good selection, generous seed portions, and very informative info for each variety. Also a very good selection of OG publications.

Since you are in zone 7, I have to respectfully disagree with the above, and highly recommend Baker Creek (sorry Jay). While it is true that little info comes with the seed pack, they have a detailed planting guide on their website, plus their own forums. They also simply have the _best_ selection of cowpeas, melons, squash, eggplant, and many Asian heirlooms, all acclimated to Southern climate.

For more varieties acclimated to the South, try Southern Exposure Seed Exchange. They also have many seed saving supplies, should you find yourself headed in that direction.

All of the above have websites, and all except Southern Exposure have free catalogs (last I checked). Southern Exposure will download a .pdf version of their catalog for free.

If you can't find something anywhere else, I would be remiss if I did not mention contacting a Seed Savers Exchange _member_, who has access to many varieties not listed in SSE's catalog. I am one of them. (shameless self promotion) ;-)